Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Primary Study Investigators

Chest. 1997 Apr;111(4):970-80. doi: 10.1378/chest.111.4.970.


Study objective: To (1) determine appropriate decision thresholds and diagnostic accuracies for pleural fluid (PF) tests that discriminate between exudative and transudative pleural effusions, and (2) evaluate the quality of the primary investigations.

Design: Formal meta-analysis of studies that report the diagnostic value of pleural fluid tests.

Setting: Data collected from international academic medical centers.

Patients: Hospitalized patients undergoing thoracentesis for pleural effusions.

Interventions: Primary investigators were requested to transmit original data from patients described in their studies.

Measurements and results: Eight primary studies described 1,448 patients with one or more of the following tests: protein (P)-PF, P-PF/serum ratio (R), bilirubin (BILI)-R, lactate dehydrogenase (LDH)-PF, LDH-R, cholesterol (C)-PF, C-R, and albumin gradient. We found that all eight tests had similar diagnostic accuracies when evaluated by receiver operating characteristic (ROC) analysis except for BILI-R, which was less diagnostically accurate. Decision thresholds determined by ROC analysis differed from previously reported values for LDH-PF (>0.45 upper limits of normal) and C-PF (>45 mg/dL). Paired and triplet test combinations tended to have higher diagnostic accuracies compared with individual tests, but examination of the odds ratios with 95% confidence intervals did not identify a clearly superior test combination. Limitations of the primary studies presented a high likelihood of bias affecting their results.

Conclusions: Several strategies exist for clinicians in utilizing PF tests to classify effusions as exudates or transudates but accurate interpretations of these test results will require better designed studies.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Albumins / analysis
  • Bilirubin / analysis
  • Cholesterol / analysis
  • Exudates and Transudates / chemistry*
  • Female
  • Humans
  • L-Lactate Dehydrogenase / analysis
  • Male
  • Middle Aged
  • Pleural Effusion / chemistry*
  • Proteins / analysis
  • ROC Curve
  • Sensitivity and Specificity


  • Albumins
  • Proteins
  • Cholesterol
  • L-Lactate Dehydrogenase
  • Bilirubin